This invention relates to modem connections for portable computers, and more particularly to a portable computer having a built-in modem and facility for using a telephone connection in a docking station for the portable computer.
Portable computers of the laptop or notebook size usually have modem devices so that telephone transmission is available for email or facsimile functions. This facility is a primary forte of a portable computer as it is often used by persons who travel and must make connections to a home office. Usually, a modem card is employed of the PCMCIA type, i.e., a separate plug-in card or circuit board. When the portable computer is operated in a stand-alone mode, the modem card is connected to a telephone line using a standard RJ-11 connector. An example of a modem configuration for a portable computer is disclosed in my U.S. Pat. No. 5,428,671, assigned to Compaq Computer Corporation, assignee of this invention.
Many portable computers have a corresponding docking station so that the computer may be operated in a permanent setting such as an office or home, in the manner of a desk-top computer. The docking station usually has a power supply arrangement so that the portable computer need not operate on battery power when docked, and often has a full-sized keyboard and display associated with it. Connections may be made to a network, via an ethernet card or the like, and various peripheral such as additional disk drives, a printer, etc., may be located at the desktop site, connected to the docking station.
An advantageous construction of a portable computer with a docking station would allow all of the peripherals located at the docking station to be semi-permanently in place, so the coupling of the portable with the docking station is accomplished with a minimum of manual steps. That is, the fewer plug-in connections to be made when berthing the laptop into the docking station, the better. For peripherals such as the keyboard and monitor, this is easily accomplished because the components are merely duplicated. The LCD display used in the laptop is replaced by a full-sized CRT type monitor, and the small keyboard and touchpad or trackball devices built into the laptop are replaced by a full-sized keyboard and mouse or trackball.
Previously it has been the practice to utilize the phone jack on the modem card of the portable computer itself to establish a phone line connection, even when the portable computer is berthed in the docking station. While this is efficient and reliable, the requirement for performing a separate plug-in operation for the phone cord, as well as the clutter added to a desk-top environment by an additional cord, leave this solution to be less than optimum. Preferably, the user should be able to make a single-step connection and not unduly add to the jumble of cords usually associated with desktop computer equipment.
It would be a simple task to route a phone line connection from a phone jack on the docking station to the plug-in connection between the laptop and the docking station, so that a phone line could remain in place for the docking station and thus for the laptop when it was berthed. However, the phone line is a high voltage line, compared to the internal conductors of a portable computer, and so the phone line is not compatible with the other internal wiring. Thus, the phone connection cannot be routed with the other connections which are made between the laptop and the docking station.